Most harbours now provide waste containment receptacles into which marine operators, such as fishermen, are required to dump waste fluids including used lubricating oils and bilge fluids. Such fluids, if dumped into the sea would damage the environment and it is necessary to avoid such unwanted pollution. The waste fluids must therefore be collected on board the vessels while at sea and then pumped into containment receptacles in the harbour for subsequent disposal. Inasmuch as the waste fluids contain volatile substances, including hydrocarbons, it is essential that the containment vessels be vented to prevent explosive overpressure conditions from developing.
Most containment receptacles are provided with an inlet, an outlet and a vent stack. Usually the vent stack will be sufficient for the venting of air during filling and for the normal venting of volatile gases that may be generated within the receptacle. However there is a need for additional venting under emergency overpressure conditions, conditions which may develop more frequently with greater use of such waste containment receptacles.